Active ray curable inks are known as an ink by which an image having high scratch resistance and adhesiveness can be formed even on a recording medium that does not have ink absorbability. In an image forming method using an active ray curable ink, an image is formed by applying liquid droplets of the ink to a recording medium and then curing the ink by irradiation with active rays such as ultraviolet rays.
However, in an image forming method using a conventional active ray curable ink, there is a problem in that combining of adjacent dots cannot be suppressed particularly at the time of high-speed printing, and thus image quality is deteriorated. As a method for preventing combining of adjacent dots, a technique of adding a gelling agent to an active ray curable ink is proposed.
Efforts for further enhancing the quality of an image formed by an ink containing a gelling agent are also known. For example, in Patent Literature 1, an ink applied to a recording medium is caused to reflow by heating through irradiation with an infrared ray so as to reduce the viscosity of the ink, and thus the surface of the ink is smoothened. Further, in Patent Literature 2, when an ink of which gel rheology conforms well with a paper substrate is used, the gloss of printed region matches the gloss of non-printed region.
As another method for enhancing the image quality, a technique is known in which another active ray curable ink is additionally applied to an active ray curable ink, which has been cured by irradiation with an active ray, so as to perform coating, for the purpose of providing gloss to a printed image or providing resistance to impact from the outside. In Patent Literature 3, the gloss of an image is controlled by an overcoat composition containing a gelling agent, a curable monomer, a curable wax, and a photoinitiator.